Apparatus for teaching electrical concepts

ABSTRACT

A method of teaching electrical concepts such as voltage, current and resistance by the use of an analogous mechanical model is disclosed in which potential is simulated by releasing a ball from an elevated position, and electron conduction is simulated by the arrangement of a plurality of abutting balls on a track that are contacted by the released ball.

United States Patent Muhlfeld 51 June 6, 1972 1 APPARATUS FOR TEACHINGWelch Scientific CO. Catalog, pages 66 and s5.

ELECTRICAL CONCEPTS Primary Examiner-Wm. H. Grieb [72] Inventor: FrankMuhlfeld, 300 North Street, Anomey sandoe, nopgood and calimafdeGreenwich, Conn. 06830 221 Filed: Apr. 6, 1970 211 App]. No.1 25,734[57] ABSTRACT A method of teaching electrical concepts such as voltage,cur- [52] U.S.C|. ..35/l9A rent and resistance by the use of ananalogous mechaniCal [51 Im. Cl, model is disclosed in which potentialis simulated by releasing [58] Field of Search ..35/19 R, 19 A, 10 aball from an elevated position, n l n n i n is simulated by thearrangement of a plurality of abutting balls [56] References Cited on atrack that are contacted by the released ball.

OTHER PUBLICATIONS Chicago Apparatus Co. Catalog, page 296.

5 Claims, 4 Drawing Figures APPARATUS FOR TEACHING ELECTRICAL CONCEPTSThis invention relates generally to teaching methods and ap paratus, andmore particularly to a method for demonstrating the meaning ofelectrical concepts by the use of mechanical analogs. v

In the teaching of relatively abstract subject matter it has been foundto be of great value to represent the subject matter by the use ofmechanical models which perform in an analogous manner to the abstractconcept. Typical of these teaching methods is the one with which thepresent invention is involved, to wit, the teaching of electricalconcepts such as the meaning of electromotive force, current,resistance, and the like.

It has been customary in the past to describe electrical concepts interms of their analogy to hydraulic circuits in which the flow of wateris analogous to the flow of electric current, and a pump is analogous toa voltage source. An analogy of this type has been found to be helpfulbut its utilization, such as in schools, has been limited since thisapproach assumes that the student is familiar with hydraulics. Moreover,demonstrations of analogous hydraulic systems have been limited by thehigh cost and cumbersome nature of the equipment required for suchdemonstrations.

It is an object of this invention to provide a method and apparatus forteaching electrical concepts by the use of a readily comprehendedmechanical analogy.

It is a further object of the invention to provide a teaching method ofthe type described in which the necessary mechanical components arerelatively inexpensive and easily assembled and manipulated in thedemonstration.

It is another object of the invention to provide a teaching method ofthe type described in which subtle electrical concepts can be madereadily understood to the student in an effective manner which holds theattention of the student.

The present invention provides a simulation of an electrical circuit byan analogous mechanical model in which the circuit is comprised of ahigh voltage source, air gaps, wires and resistors. The simulatingmechanical apparatus is comprised of a track having an elevated portionand a lower level portion on which a plurality of abutting balls arearranged. Voltage is simulated by releasing a ball from the elevatedportion which contacts the balls on the track level portion. Anopenearea on the track, that is, an area in which there are no balls,simulates an air gap while a row of side-by-side abutting ballscorrespond to a conductor. A compressible member such as a sponge-likewafer may be interposed between the balls to simulate a resistor.

To the accomplishment of the above and to such further objects as mayhereinafter appear, the present invention relates to a teachingapparatus and method substantially as defined in the appended claims andas described in the following specification taken together with theaccompanying drawings in which:

FIG. 1 is a schematic diagram of an electrical circuit which may besimulated by the apparatus of the invention;

FIG. 2 is a perspective view of a first portion of the teachingapparatus of the invention;

FIG. 3 is a perspective view of a second portion of the apparatus foruse with the portion of FIG. 2 in the practice of the invention; and

FIG. 4 is a perspective view of the portion of FIG. 2 modified toillustrate the concept of electrical resistance.

The present invention has for its purpose the illustration of electricalconcepts by means of a mechanical analog system, in which the analogiesare readily grasped and appreciated by the student.

FIG. 1 is a schematic diagram of a circuit which exhibits some of thebasic electrical properties that can be represented and demonstrated bythe method and apparatus of the invention. In that circuit, a variablehigh voltage source has one terminal connected by a conductor 11 to apoint 12. An air gap 13 is defined between point 12 and a point 14spaced therefrom. Point 14 is in turn connected by a length of conductor11a to a point 15 which defines with a spaced point 16,

a second air gap 17. Point 17 is connected to the other terminal ofvoltage source 10 by a conductor 18.

In a classroom demonstration of the circuit of FIG. 11, source 10 isvaried until electrons jump across air gaps l3 and 16. A briefdiscussion would then be given of the need of a minimum or thresholdvoltage required to establish sparking across the air gaps, and thenature of electronic flow across the gaps and through the conductors inthe circuit. These concepts are then illustrated by the mechanicalanalogs obtained by the use of the apparatus of FIGS. 2 and 3.

The mechanical apparatus shown in FIG. 2 generally designated 20'comprises a track 21 shown resting on a horizontal surface 22. Track 21comprises an adjustable elevated platform 23, a long level portion 24,and a sloping portion or ramp 25 connecting platform 23 and levelportion 24 and being pivotably connected to the latter. A centrallongitudinal groove 26 extends continuously along the flat and slopingportions of the track, and a group of abutting spherical metallic balls27 are positioned at the right end of track 21 in groove 26.

A second track apparatus illustrated in FIG. 3 generally designated 28is preferably utilized in the practice of the invention along with theapparatus of FIG. 2 to provide a basis for comparison as will bedescribed below. Track apparatus 28 is substantially identical to trackapparatus 20 and corresponding elements of the former are designated bythe reference numerals in FIG. 2 to which the subscript a has beenadded. Track apparatus 28 differs from track apparatus 20 in that twospaced groups of balls 29 and 30 are arranged within groove 26a alongthe level portion 24a of track 210.

In operation, a ball 31 is placed on elevated platform 23, released andallowed to roll down the ramp 25 in the groove 26 to the level part ofthe track until it reaches the inwardmost one of balls 27 at which timeit will come to an abrupt halt. Similarly in the apparatus of FIG. 3, aball 31 released down ramp 250 will contact the innermost one of balls29a and will come to an abrupt stop. However, as is known, according toprinciples of the conservation of energy and momentum, the impact ofball 31 on the innermost one of the balls 29:: in group 29 will causethe outermost ball 29b to leave group 29 and proceed along groove 26a ata velocity substantially equal to the impact velocity of ball 31 untilit reaches the innermost ball in the group of balls 30 at which timeball 29b will come to an abrupt halt.

Varying the height of ramp 25 as by operating an adjusting linkagemechanism 32 positioned beneath the ramp, results in varying velocitiesof the ball along the level portion of the track since the potentialenergy of the impact ball varies directly as the height of the ramp. Asis known the potential energy is converted to kinetic energy when theimpact ball reaches the level portion of the track. In the mechanicalsystem of FIGS. 2 and 3, the adjustable ramp is analogous to thevariable voltage source 10 of the circuit of FIG. 1, the open trackareas, e.g. the spacing between balls 29 and 30 in the FIG. 3 apparatus,is analogous to the air gaps in the circuit, and the groups of abuttingballs 27, 29 and 30 are analogous to the conductors of the circuit.

Thus, varying the release height of the impact ball 31 corresponding toan increase in the voltage source 10 produces an increase in thevelocity of the balls in the open track space (the air gaps in thecircuit). In this manner the student viewing the mechanical systemquickly comprehends the phenomenon of the increase in air gap conductionas a result of an increase in the potential across the gap.

To illustrate the principle that the speed of the electrons in.

the air gap is not equal to the speed of electron flow in the conductor,and is in fact much slower, the ramps of track apparatus 20 and 28 areboth placed at substantially the same level and impact balls 31 and 310are released simultaneously from their respective elevated platforms.Both balls arrive'at the level portion of the track at the samevelocity. However, the ball in track apparatus 28 (FIG. 3) upon strikingthe innermost ball 29b in group 29 will immediately cause the outermostball 29b in that group to leave the group at the same velocity as theimpact ball. Ball29b then proceeds toward the group of balls 30 until itstrikes the innermost ball in that group. Meanwhile, the impact ball 31moving along apparatus 20 continues along the level portion 24 of track21 until it strikes the innermost ball in group 27. That impact willoccur later in time than the impact of ball 29b on the innermost ball ingroup 30. v This comparative demonstration clearly indicates the natureof electron transfer or flow in a conductor with each ball in group 29representing a unit of charge, such as an electron or 1 coulomb, in thatrather than a single electron flowing completely through the conductoras it would through the air ap, the conduction in the conductor is theresult of the transfer between adjacent electrons in the conductor assimulated by the transfer of velocity between the abutting balls ingroup 29 between balls 29a and "29b. Significantly, this demonstrationindicates to the student that the rate of energy flow (or current)through theconductor is greater than that through the air gap (along theopen space in the track).

' The concept of resistance maybe readily demonstrated by "themodification of the track apparatus 28 of FIG. 3 as illustrated in FIG.4 in which a sponge like wafer 33 of compressible, energy-absorbingmaterial is interposed between any adjacent two balls in group 29. Thiscorresponds to the connection of a resistance (not shown) in series withconductor 11a between circuit points 14 and 15 in any known manner suchas by the use of a double-pole switch.

In the demonstration of the circuit of FIG. 1 as modified by theinclusion of the series-connectedresistance, it will be noticed that ahigher voltage from source is required to initiate a spark across theair gaps l3 and 16. In the apparatus of FIG. 4, when a ball is releaseddown ramp 25a it will again travel at an initial velocity along the opensection of track corresponding to the electron flow across air gap 13,until it strikes the innermost ball 29a in group 29. That impact energywill be in part absorbed by the compressible wafer 33 and the ball 29bleaving the group 29 will travel at a reduced velocity along the portionof track between groups 29 and 30 (corresponding to air gap 16 in thecircuit).

If a thicker wafer were used or if two or more wafers were interposed ingroup 29, the final velocity of the ball 29b would be even furtherreduced. Thus, the concept of electrical resistance may be visuallydemonstrated by the apparatus of the invention, by demonstrating theloss of kinetic energy from the impact ball 31 to the final ball 29b.Similarly, in the electrical circuit, the greater the amount ofresistance placed between points 14 and 15, the greater will be the lossof electrical energy, and the fewer charges that are caused to flowacross air gap 16 in a given period of time.

Av dramatic finale for the demonstration may be achieved in the practiceof the invention through the simultaneous use of the apparatus of FIGS.2 and 4 by placing a sufficient number of sponge wafers 33 in group 29so as to cause simultaneously released impact ball 31 of FIG. 2apparatus, and ball 31a of the FIG. 4 apparatus to arrive simultaneouslyat the innermost balls in groups 27 and 30 respectively. The resistancein the analogous conductor i.e. group 29, is now made substantiallyequal to the resistance of the corresponding portion of open track inthe FIG. 2 apparatus, i.e. the analogous air gap.

The teaching method and apparatus of the invention is thus highlysuitable for demonstrating basic electrical concepts such as conduction,resistance, and voltage to a group of students. As the students level ofunderstanding is increased, the method and apparatus can be furtherutilized to advantage in demonstrating more advanced concepts such asKirchoff's laws, air gap resistance, spark visibility phenomena, and thelike.

While the principles of the invention have been described in connectionwith a specific embodiment thereof, it is to be clearly understood thatthis description is made only by way of example and not as a limitationto the scope of the invention.

I claim: l. A method for demonstrating electrical concepts comprisingthe steps of simulating a variable voltage source by providing a trackhaving a variable raised portion on one end thereof and a level sectionin communication with said raised portion, releasing a ball from saidraised portion, simulating an electrical conductor by a plurality ofballs on said level section, adjacent ones of said plurality of ballsbeing in substantial abutting relation with one another, simulating anair gap in an electrical circuit by providing an open portion free ofsaid balls on said level section, and interposing at least one energyabsorbing member between adjacent ones of said balls to simulateelectrical resistance.

2. The method of claim 1, in which two of said tracks are provided, eachof said tracks having a first plurality of said balls on one end of saidlevel section, and one of said tracks has a second plurality of ballsspaced on said level section from said first plurality of balls, therebydefining said open portion of track therebetween.

3. The method of claim 2, further comprising the step of substantiallysimultaneously releasing said ball from the raised portions of both ofsaid tracks.

4. Apparatus for demonstrating electrical concepts comprising first andsecond tracks having a raised ramp portion and a level section incommunication therewith and a longitudinal groove extending into saidraised portion and along said level section, a first plurality of ballsin abutting relationship V arranged in said groove in each of saidtracks, a second plurality of balls arranged in abutting relationship insaid groove and spaced from said first plurality of balls in only one ofsaid tracks, and an energy-absorbing member interposed between adjacentballs of said second plurality of balls.

5. The teaching apparatus of claim 4, further comprising means foradjusting the elevation of said ramp portion with respect to said levelsection.

1. A method for demonstrating electrical concepts comprising the stepsof simulating a variable voltage source by providing a track having avariable raised portion on one end thereof and a level section incommunication with said raised portion, releasing a ball from saidraised portion, simulating an electrical conductor by arranging aplurality of balls on said level section, adjacent ones of saidplurality of balls being in substantial abutting relation with oneanother, simulating an air gap in an electrical circuit by providing anopen portion free of said balls on said level section, and interposingat least one energy absorbing member between adjacent ones of said ballsto simulate electrical resistance.
 2. The method of claim 1, in whichtwo of said tracks are provided, each of said tracks having a firstplurality of said balls on one end of said level section, and one ofsaid tracks has a second plurality of balls spaced on said level sectionfrom said first plurality of balls, thereby defining said open portionof track therebetween.
 3. The method of claim 2, further comprising thestep of substantially simultaneously releasing said ball from the raisedportions of both of said tracks.
 4. Apparatus for demonstratingelectrical concepts comprising first and second tracks having a raisedramp portion and a level section in communication therewith and alongitudinal groove extending into said raised portion and along saidlevel section, a first plurality of balls in abutting relationshiparranged in said groove in each of said tracks, a second plurality ofballs arranged in abutting relationship in said groove and spaced fromsaid first plurality of balls in only one of said tracks, and anenergy-absorbing member interposed between adjacent balls of said secondplurality of balls.
 5. The teaching apparatus of claim 4, furthercomprising means for adjusting the elevation of said ramp portion withrespect to said level section.